xppq

Fast XML parser and preprocessor addon for Node.js.

Install

npm install xppq

For other platforms as Windows, you need C++ development tools to be installed.

Description

Parses a stream containing XML formatted data and calls a callback for each token.
Provides a read stream which takes another read stream an applies an XML preprocessor to it.

Usage

const xppq = require('xppq');
const fs = require('fs');
 
function callback( token, tag, attribute, value )
{
    switch ( token ) {
    case xppq.tokens.ERROR :
        write( ">>> ERROR:  '" + value + "'\n" );
        break;
    case xppq.tokens.START_TAG :
        write( "Start tag: '" + tag + "'\n" );
        break;
    case xppq.tokens.ATTRIBUTE :
        write( "Attribute: '" + attribute + "' = '" + value + "'\n" );
        break;
    case xppq.tokens.VALUE :
        write( "Value:     '" + value.trim() + "'\n" );
        break;
    case xppq.tokens.END_TAG :
        write( "End tag:   '" + tag + "'\n" );
        break;
    default:
        throw( "Unknown token !!!");
        break;
    }
}
 
const file="SomeFileContainingXMLFormattedData";
 
// XML parsing WITHOUT preprocessing. 
xppq.parse( fs.createReadStream( file ), callback );
 
// XML parsing WITH preprocessing. 
xppq.parse( new xppq.Stream( fs.createReadStream( file ) ).on( 'error', (err) => console.error( '>>> ERROR : ' + err ) ), callback );

Error handling

For the preprocessing stream, when an error occurs, an error event is launched.

If an error occurs during parsing, the callback is called with the token parameter containing xppq.tokens.ERROR, and value containing a description of the error.

Error handling for both case is illustrated in the above section.

Example

Given following XML data :

<?xml version="1.0" encoding="UTF-8"?>
<SomeTag xmlns:xpp="http://q37.info/ns/xpp/" AnAttribute="SomeAttributeValue">
 <SomeOtherTag AnotherAttribute="AnotherAttributeValue">TagValue</SomeOtherTag>
 <xpp:define name="SomeMacro">
  <xpp:bloc>Some macro content !</xpp:bloc>
 </xpp:define>
 <YetAnotherTag YetAnotherAttribute="YetAnotherAttributeValue">
  <xpp:expand select="SomeMacro"/>
 </YetAnotherTag>
</SomeTag>

With the callback from previous section, you will obtain :

without preprocessing :

Start tag: 'SomeTag'
Attribute: 'AnAttribute' = 'SomeAttributeValue'
Start tag: 'SomeOtherTag'
Attribute: 'AnotherAttribute' = 'AnotherAttributeValue'
Value:     'TagValue'
End tag:   'SomeOtherTag'
Start tag: 'xpp:define'
Attribute: 'name' = 'SomeMacro'
Start tag: 'xpp:bloc'
Value:     'Some macro content !'
End tag:   'xpp:bloc'
End tag:   'xpp:define'
Start tag: 'YetAnotherTag'
Attribute: 'YetAnotherAttribute' = 'YetAnotherAttributeValue'
Start tag: 'xpp:expand'
Attribute: 'select' = 'SomeMacro'
End tag:   'xpp:expand'
End tag:   'YetAnotherTag'
End tag:   'SomeTag'

with preprocessing :

Start tag: 'SomeTag'
Attribute: 'AnAttribute' = 'SomeAttributeValue'
Start tag: 'SomeOtherTag'
Attribute: 'AnotherAttribute' = 'AnotherAttributeValue'
Value:     'TagValue'
End tag:   'SomeOtherTag'
Start tag: 'YetAnotherTag'
Attribute: 'YetAnotherAttribute' = 'YetAnotherAttributeValue'
Value:     'Some macro content !'
End tag:   'YetAnotherTag'
End tag:   'SomeTag'